In the processing of chickens, turkeys, and other types of poultry through a poultry processing plant for defeathering, evisceration, cut-up, and packaging for delivery and sale, it is highly desirable to form as many of the processing steps as possible with automated machinery. This is necessary to minimize the more expensive manual handling of poultry carcasses as well as to uniformly cut apart the carcasses.
In recent years, poultry carcasses have been suspended by their legs from a suspended "overhead" conveyor system and many of the processing steps have been performed on the poultry carcasses as they are moved in series along the overhead conveyor system. For example, the poultry carcasses can be defeathered, decapitated, opened, and eviscerated while being advanced progressively through a poultry processing plant on an overhead conveyor system. It is further desired that the poultry carcasses be segmented while continuing their travel on the overhead conveyor system, so as to avoid the manual handling of the poultry carcasses when performing the cutting functions. Examples of such on-line cup-up operations are shown by U.S. Pat. Nos. 5,015,213 and 5,035,673. However, it is still a common practice to remove the poultry carcasses from the overhead conveyor system in order to sub-divide the poultry carcasses.
A problem with cutting apart the poultry carcasses as they are carried by the overhead conveyor system generally has been that it is difficult to make clean and accurate cuts between the bones of a joint to separate the poultry carcasses into parts. Since the joints usually are still connected by the tissue or only partially separated when the cutting blade begins its movement through the joints, there is a risk that the cutting blade will engage the bones of the joints. Such engagement tends to create fragments of bone that can become lodged in the meat of the poultry parts. Such bone fragments pose health risks to the purchasers and consumers of the poultry parts and cause the poultry parts to be down graded in quality.
Additionally, when poultry products are cooked, it is desirable to cook the products rapidly so that the heat energy is conserved. It is highly desirable to cook the products uniformly so that the thinner portions of the product are not overcooked and thicker or more massive portions of the poultry parts are not undercooked. When the back of a poultry carcass is not separated from the thighs of the poultry carcass prior to being cooked, it is difficult to obtain uniform cooking of the poultry part. This is due to the thickness of the poultry part in the area of the joint between each thigh bone and back, which is greater than, for example, the leg of the product. As a consequence, the cooking process must be performed at a lower temperature and for a long time in order to have the heat properly penetrate the massive portion of the thigh/back at the thigh joints, in order to properly cook this part of the poultry carcass.
In order to increase the rate of cooking undivided sections, it is possible to open and dislocate the joint between them so as to reduce the density of the meat/bone in this area of the poultry carcass and to expose the ends of the bones which enables the heat to more easily reach the bone ends. This dislocation or separation of the joint elements typically requires an additional step in the process of the handling of the poultry carcasses.
Therefore, it can be seen that it would be desirable to provide an improved method and apparatus for opening and dislocating the thigh joints of poultry carcasses as the poultry carcasses are moved in series along an overhead conveyor of a poultry processing system in which the poultry carcasses are otherwise processed by automated equipment so as to avoid further manual handling of the poultry carcass parts to open the joints.